This invention relates generally to the field of door security systems. More specifically, this invention relates to an improved electrically energizable, solenoid operated, door-strike mechanism that is easily switchable, to either of two different selected modes of operation. In one mode of operation the mechanism is in a fail-safe mode, wherein, if power to the solenoid fails, a keeper moves to allow a door to be safely opened. The other mode is called fail-secure, wherein, if power to the solenoid fails, the keeper secures the door against opening.
Electric strikes for securing hinged or swinging doors are well-known in the field of door security systems. The electric strikes are employed with doors having projectable deadbolts or latch bolts that engage the electric strike. The electric strike can be configured to secure the door alone, or in combination with other conventional security systems. The electric strike typically is mounted to the door frame and defines an opening in the jam face of the door frame for receiving the latch bolt and/or deadbolt from the lockset mounted to the door. The electric strike further defines an opening in the frame face contiguous with the opening in the jam face of the door frame. A pivotal keeper on the electric strike selectively closes the opening in the frame face. A bolt, projecting from the edge of the door, engages the electric strike through the opening in the jam face. Actuation of the electric strike locks or unlocks the keeper. The keeper is pivotable to uncover or open the frame face opening to allow the bolt to swing there through, and thereby allow opening of the door. The keeper is pivoted by the door being pushed, whereby the bolt engages the keeper of the strike.
The lock assembly of a conventional electric strike is commonly operated by a solenoid. The solenoid is typically configured to be spring-biased so that energization of the solenoid overcomes the biasing force of the spring to either lock or unlock the electric strike. In a first configuration the power must be continuously supplied to the solenoid in order to maintain the electric strike in a locked condition. This configuration requires a relatively high and continuous input of energy and therefore, typically requires electrical wiring to the doorway from an electric line source.
Similarly, electric strikes that are configured to unlock upon energization can also require a continuous supply of energy in order to maintain the lock in unlocked condition.
There is a need for electrically-controlled strike mechanisms of simple, compact, construction for securing doors against opening (fail-secure mode), and also for allowing door opening (fail-safe mode), in the case of power failure. Most mechanisms permitting these two functions require two different strike devices, each device permitting only one of these functions. Current mechanisms which embody the two functions in a single mechanism require complicated disassembly and reassembly in order to accommodate both modes of operation. This invention permits alternating between fail-safe and fail-secure operation by simply turning a single part, an actuator, 180xc2x0.
Briefly stated, the electric strike in the preferred form employs a solenoid to transform the electric strike between the locked and unlocked states. The solenoid allows for the use of an on-board power source, such as batteries, or an exterior power source to energize the electric strike. In the event that the power source is terminated, for example, because of power failure, it may be desired that the electric strike automatically engages in a fail-safe or alternatively a fail-secure mode. The electric strike includes a means operatively connected between the solenoid and the keeper for causing the keeper to assume a fail-safe condition allowing the keeper to pivot when the solenoid is in either position, or alternatively a fail-secure condition preventing the keeper from pivoting when the solenoid is in either position. In the present invention, the means connecting the solenoid to the keeper can be configured in either mode by simply opening the strike, removing a solenoid assembly and actuators, turning the actuator over and reinserting the removed parts. This permits easy selection of either mode by an unskilled human operator, in the field, in a short period of time, without complicated disassembly and reassembly of the strike mechanism.
The actuator is a simple, unique, mechanical connection between a solenoid assembly and a lock link that permits or prevents the keeper from unlocking. The actuator is designed to operate in either of two positions. With one side up, the actuator is spring-biased to push the lock link into a fail-safe mode if the solenoid is unpowered. The actuator can be removed and reinserted with the other side or opposite side up. In this second position, the actuator is spring-biased to push the lock link into a fail-secure mode if the solenoid is unpowered.
It is an object of the invention to provide an improved and relatively compact electric door strike for controlling access through a doorway with a mechanism that permits alternatively selecting a fail-safe condition or alternatively fail-secure condition with a simple easy mechanical reconfiguration that can be accomplished quickly in the field.
It is another object of the invention to provide an electric strike mechanism that can be selectively configured in a fail-safe or fail-secure mode without a special operator, special tools or the addition of external devices.
These and other objects of the invention will become apparent from a review of the specification and the drawings.